Apparatus for purging air from engine cooling systems



March 28, 1961 E. J. H. BENTZ 2,976,859

APPARATUS FOR PURGING AIR FROM ENGINE COOLING SYSTEMS Filed April 20, 1960 INVENTOR. ERWI/V J15. BE/yy'z BY ATTORNEYS Stats APPARATUS FOR PURGING AIR FROM ENGINE COOLING SYSTEMS Filed Apr. 20, 1960, Ser. No. 23,555

4 Claims. (Cl. 123-4154) This invention relates to apparatus for purging air from engine cooling systems and particularly to an apparatus or system wherein air or other gaseous fluid trapped in certain parts of a cooling system is induced to flow out of the area where it is trapped by the provision of a low pressure cell in the system communicating with the area to be purged.

The thermostat or water temperature regulator of an engine provides a restriction to circulation of the coolant therein disposed in an area which is between the high and low pressure sides of the water pump. The present invention takes advantage of the lower pressure existing at the downstream side of the regulator. A small cell or chamber is provided in this area and connected as by a tube with the area to be purged. As this provides a by pass of the regulator, the present invention also includes means to limit the quantity of the coolant which might flow through the bypass and afiect the efliciency or accuracy of the regulator.

It is the object of this invention to provide a simple, inexpensive and positively actuated air purging system and apparatus for the cooling system of engines.

Other objects and advantages of the invention are made apparent in the followingspecification wherein the invention is described in detail by reference to the accompanying drawing.

The drawing is a view in side elevation of a portion of an internal combustion engine equipped with air purging apparatus in accordance with the present invention and with parts broken away and shown in section to illustrate the manner in which the invention functions.

In the drawing, a portion of an engine cylinder block is shown at and a cylinder head at 11. A water pump for circulating coolant through the engine is illustrated at 12 and is actuated through a pulley 13 in the conventional manner by a belt, not shown, which connects the pump with the crankshaft of the engine. A line 14, which often includes a heat exchanger 15 as illustrated, forms communication between the discharge side of the pump 12 and the cylinder block 10. Coolant is directed into the block to flow around cylinder liners 16 in which pistons such as illustrated at 17 are reciprocated by detonation of fuel in the combustion chambers of the cylinder liners. This fuel is introduced into the combustion chambers by conventional means, as for example the precombustion chambers of a compression ignition engine, one of which is shown at 18. The coolant passing through the cylinder block in the direction generally represented by arrows passes upwardly through suitable ports and dispersing members 19 to surround and cool the precombustion chambers and valve chambers, not shown, in the cylinder head. The coolant then flows forwardly through an opening 20 at the forward end of the cylinder head into a thermostatic valve chamber formed by a wall 21, upwardly through the thermostatic valve generally indicated at 22 and thence through a fitting 23. It then fiows through a suitable conduit and radiator, schematically shown at 24, wherein it is cooled and returned as 2,976,859 Patented Mar. 28,1961

through a connection 24a to the intake side of the pump 12.

The thermostatic valve herein illustrated is of a conventional type in which an expansible substance in a chamber 25 opens the valve element 2.6, which is normally biased closed by a spring 27 when the temperature of the coolant is below a predetermined value. With the temperature of the coolant below this value, as for example upon starting of a cold engine, the valve 26 is closed and the coolant bypasses the radiator to flow downwardly through a bypass line 28 to the intake side of the pump.

In many vehicular engines, air becomes entrapped in the circulating coolant and collects at a high point in the system which is toward the rear of the cylinder head when the vehicle is operating on a downhill slope. This air prevents transfer of heat from the cylinder head to the coolant and the temperature of the head casting often rises to a point at which cracking of the casting occurs.

In accordance with the present invention, a low pressure cell 30 is provided in the wall 21 of the thermostatic chamber and is connected by a line 31 and fitting 32 with the interior of the cylinder head in the area where air becomes trapped. The top and bottom walls of the cell 30 are provided with restricted orifices as shown at 33 and 34, respectively, and, for convenience in manufacture, the cell may be formed as a passage through the wall 21 which supports the thermostatic regulator with both ends closed by plugs, as shown, in which the restricted orifices are formed.

With the construction shown, the pressure of the coolant in the system forces air, or air laden coolant, from the rear end of the cylinder head out through the tube 31 and orifice 33 so that it reaches the top tank of the radiator which is vented to atmosphere as by a tube 24b. This results from the fact that the pressure below the cell 30 is greater than the pressure above it and the median pressure within the cell resulting from communication through the orifices 33 and 34 is considerably lower than the pressure of coolant in the cylinder head. Assuming for example that the pump develops a pressure of approximately 30 p.s.i. at its discharge end and, allowing for loss of pressure of approximately 10 pounds as the coolant fiows through the cylinder block and head, pressure below the chamber 30 will be 20 p.s.i. With the thermostatic valve closed, the pressure above the cell in the area which communicates with the top tank of the radiator will be substantially at atmospheric level. Since this pressure drop across the chamber is divided by communication through the orifices 33 and 34, the actual pressure Within the chamber 30 will be about 10 p.s.i. whereas the pressure in the rear end of the cylinder head below the fitting 32 will be 20 p.s.i. or possibly slightly greater. Even with the thermostat open and all of the coolant in the radiator being circulated by the pump, which increased flow results in reducing the pressure drop across the pump, the pressure below the cell 30 will remain as high as 5 to 6 p.s.i. as contrasted to atmospheric pressure above the cell. Consequently the resultant pressure in the cell of half this value is still effective to induce positive flow of the air laden coolant through the tube 31 and to the radiator top tank.

The exact location of the cell 30 herein illustrated is not to be taken as critical so long as it is disposed between high and low pressure areas and provided with orifices to produce a modified pressure in the cell which is lower than that of the area from which air is vented. In fact the entire length of the tube 31 may be included as a portion of the chamber 30 by closing the orifice 34 and providing a restricted orifice in the fitting 32. One reason for providing small or restricted orifices for communication with the chamber 30 is that the chamber provides a bypass around the temperature regulating valve and any large volume of coolant circulated through such a bypass would render the valve ineffective.

I claim:

1. The combination with an engine having passages for the circulation of a coolant, a radiator with a vented top tank, a pump for circulating coolant through said passages and radiator, and a wall which restricts flow between said passages and the vented top tank, means to purge air from the upper portions of said passages comprising a cell extending through said Wall and communicating between opposite sides thereof through restricted orifices, and a passage connecting the interior of said cell and the upper portions of said passages.

2. The combination with an engine having passages for the circulation of a coolant, a radiator with a vented top tank, a pump for circulating coolant through said passages and radiator into the top tank thereof whereby a p pressure differential exists between the top tank and engine passages, means to purge air from the upper portions of said passages comprising a cell having a restricted orifice communicating with low pressure in the top tank and a restricted orifice communicating with the higher pressure in said passages whereby the pressure Within the cell Will be lower than within the passages, and a tube forming a communication between the interior of the cell and the upper portions of said passages.

3. The combination set forth in claim 2 in which the engine passages have a wall supporting a thermostatically controlled valve, and the cell is supported in said wall.

4. The combination set forth in claim 3 in which said wall is adjacent the forward endof the engine and the tube communicates between the cell and the uppermost passages adjacent the rear of the engine.

No references cited. 

